Synchronou Machine - Structure
Synchronou Machine - Structure rotate at contant peed. primary energy converion device of the word electric power ytem. both generator and motor operation can draw either a lagging or a leading reactive current from the upply ytem. Non-alient pole generator high peed (2-4 pole) large power (100-400 MVA) team and nuclear power plant Salient pole generator mall and mid-ize power ( 0-100 MVA) mall motor for electrical clock and other dometic device mid ize generator for emergency power upply mid ize motor for pump and hip propulion large ize generator in hydro-electric power plant
Synchronou Generator No-load excitation voltage frequency depend on the peed f = np 120 n = 120 f p E f NK f = 4.44 Φf w Ef f nφ open circuit characteritic magnetization characteritic
Synchronou Generator - loaded the tator current will etablih a rotating field in the air-gap armature reaction flux Φ a reultant air-gap flux Φ = Φ + Φ r f a
Synchronou Machine The Infinite Bu
Synchronou Machine Paralleling with The Infinite Bu ame voltage frequency phae equence phae ynchronizing lamp 1. Same f and phae equence 2. Same V and phae equence 1. Same V and f
Synchronou Motor - Starting high inertia of the rotor prohibit direct connection into upply net variable-frequency upply tart a an induction motor
Synchronou Machine Per Phae Equivalent Circuit Model armature flux, armature reaction flux, armature leakage flux Φa = Φar + Φal Φ = Φ + Φ r Er = Ear + Ef E = j I ar f ( If ) ar ( Ia ) ar a E = I j + E f a ar r magnetizing reactance ar, (reactance of armature) ynchronou reactance = ar + al ynchronou impedance Z =R a + j
Synchronou Machine Equivalent Circuit Model Norton equivalent circuit I E f f ar = If 2 N = ni re f n = 3 N e
Equivalent Circuit Model Determination of the Synchronou Reactance open circuit tet ynchronou peed tator open-circuited meaure V t (I f ) open-circuit characteritic air-gap line hort circuit tet ynchronou peed tator hort-circuited meaure I a (I f ) hort-circuit characteritic traight line flux remain at low level I a lag the E f by almot 90 becaue R a
Equivalent Circuit Model Determination of the Synchronou Reactance unaturated value from the air-gap line E Z R j (unat) da da = = a + (unat) (unat) Iba Iba E
Equivalent Circuit Model Determination of the Synchronou Reactance Saturated E = V + I ( R + j ) V r t a a al t at infinite bu operation the aturation level i defined by terminal voltage operation point c if the field current i changed the excitation voltage will change along modified air-gap line OC Eca Z(at) = = Ra + j I ba (at) (at) E I ca ba
Synchronou Machine Phaor Diagram terminal voltage taken a the reference vector generator power angle poitive E = V + I R + I j = E δ f t a a a motor power angle negative V = E + I R + I j t f a a a f E = V 0 I R I j f t a a a = E δ f convention: generating current flow out of the machine
Synchronou Machine Power and Torque V t Vt 0 f = E = E δ f Z = Ra + j = Z θ S * t a = V I I * * * * Ef Vt Ef Vt a = = * * Z Z Z Ef δ = Z θ θ Ef Vt = θ δ θ Z Z Z V t 0 convention: lagging reactive power poitive
Synchronou Machine Power and Torque complex power Vt Ef Vt S = θ δ θ Z Z 2 real power Vt Ef Vt P = co( θ δ) coθ Z Z 2 reactive power Vt Ef Vt Q = in( θ δ) inθ Z Z 2
R a neglected real power Synchronou Machine Power and Torque 3 V E P φ δ inδ t f 3 = in = Pmax reactive power Q 3φ 3Vt Ef 3V = coδ t 2 torque T = P3 φ δ δ ω = 3 Vt Ef in ω = Tmax in N m yn yn
Synchronou Machine Complex Power Locu 3 V E P φ δ inδ t f 3 = in = Pmax Q 3φ 3Vt Ef 3V = coδ t 2
Synchronou Machine Capability Curve armature heating, length of OM field heating, length of YM teady-tate tability δ
Synchronou Machine Power Factor Control machine connected to an infinite bu P= 3VtIacoφ for contant power operation Ia co φ = cont. reactive current can be controlled by field current j I = V E a t f alo P = 3 VE t f in δ E f inδ = cont
Synchronou Machine Independent Generator purely inductive load (I c i hort-circuit current) V = E I I t f a a V = I I c a = ( I I ) c a purely reitive load E I = = R R = I R t a L f c 2 L + 2 2 L + 2 quarter ellipe 2 Vt 2 Ia c 2 2 Ic ( I ) + = 1 control curve contant terminal voltage
Salient Pole Synchronou Machine the field mmf and flux are along the d-axi tator current i in phae with the excitation voltage armature mmf and flux are along the q-axi tator current i lagging the excitation voltage by 90 degree armature mmf and flux act along the d-axi, directly oppoing the field the ame magnitude of the armature mmf produce more flux in d- direction than that in q-direction magnetizing reactance i not unique in a alient pole machine
Salient Pole Synchronou Machine the armature quantitie can be reolved into two component one acting along the d-axi (F d, I d ), and the other acting along the q-axi (F q, I q ), thee component produce fluxe along the repective axe (Φ ad, Φ aq ), d-axi armature reactance d q-axi armature reactance q leakage reactance al ynchronou reactance d = ad + al q = aq + al
Salient Pole Synchronou Machine Phaor Diagram the component current (I d, I q ), produce component voltage drop (ji d d, ji q q ) E = V + I R + I j + I j Ia = I + Iq f t a a d d q q generator phaor diagram (I a lagging) d ψ internal power factor angle φ terminal power factor angle δ torque angle R a neglected
Salient Pole Synchronou Machine Phaor Diagram motoring phaor diagram (I a lagging) ψ internal power factor angle φ terminal power factor angle δ torque angle V = E + I j + I j t f d d q q ψ = φ ± δ I I I d = ainψ = ain( φ ± δ ) tanδ = V I a ± q I t a q coφ inφ I = I coψ = I co( φ ± δ ) q a a E = V coδ ± I f t d d
Power Tranfer S * t a = V I = V δ ( I j I ) t q d * = V δ ( I + j I ) t q d I d = E f V t d coδ I q = V t inδ q
Power Tranfer 2 2 t t f t V V E V S= inδ δ + 90 δ coδ 90 δ = P+ jq q d d d 2 Vt Ef Vt ( d q) P= inδ + in 2δ = Pf + P 2 d q r Q d 2 2 Vt Ef 2 in δ co = coδ Vt + q d δ if d = q, then P = V E t d f inδ Q Vt Ef = coδ d V t d 2
Power Tranfer - Torque d 2 Vt Ef Vt ( d q) P= inδ + in 2δ = Pf + P 2 d q r
Determination of d and q lip tet rotor i driven at a mall lip field winding open-circuited tator i connected to a balanced three phae upply tator encounter varying reluctance path amplitude of the tator current varie d = i V t min 2 q = i V t max 2
Speed Control of Synchronou Motor open-loop frequency control
frequency control Speed Control of Synchronou Motor P = Tω = ω = m m 4π f p 3VE t f inδ = 2π fl field current kept contant Ef = K f 1 V T = K t inδ f voltage i changed with the frequency
Speed Control of Synchronou Motor elf-controlled ynchronou motor rotor poition information i ued to decreae the tator frequency open-loop / cloed-loop control
Application ac generator contant peed operation high efficiency motor-generator et, air compreor, centrifugal pump, blower, cruher, mill power factor control, ynchronou reactor, -condener